“I don’t even know how to start this,” Adele wrote in an online letter to fans on 30 June. The previous night, she had played the second show of a sold-out, four-night residency at Wembley Stadium. These dates, in front of audiences of 98,000, were supposed to be the triumphant conclusion of her record-setting, 123-date world tour. But on stage, something had just felt wrong.

“I’ve struggled vocally both nights,” she wrote. “I had to push a lot harder than I normally do. I felt like I constantly had to clear my throat.” After the second show, Adele went to see her doctor, who told her she had damaged her vocal cords and had no option but to cancel her remaining shows. The most powerful young voice in the music business had fallen silent. “To say I’m heart broken would be a complete understatement,” she wrote.

Though only 29, Adele had been here before. Six years earlier, she had suffered a haemorrhage to her vocal cords after singing live on a French radio program. In order to repair the injury, she underwent an incredibly delicate, high-risk medical intervention: vocal cord microsurgery. In this operation, the surgeon wields miniature scalpels and forceps attached to foot-long poles that are guided down the throat to excise whatever damaged tissue is robbing the vocal cords of their elasticity, and depriving the voice of its natural timbre, range and clarity.

Adele’s surgeon, Dr Steven Zeitels, was after a nasty polyp that had formed under her epithelium, the thin outer layer of the vocal cord. Zeitels carefully snipped the layer with a scalpel, and then, with forceps, pulled back the tissue like a flap, exposing the polyp below. With a second set of forceps he pulled out the gooey, infected mass, and zapped the remaining haemorrhaged surface with a laser to stop the bleeding and prevent scarring.

The margin for error in such surgeries is measured in fractions of a millimetre. You can’t let the instruments touch any healthy tissue. Dig too deep, Zeitels knew, and he would risk damaging the superficial lamina propria, the soft, pliable underlayer of Adele’s vocal cords. If he pierced that, he told me, there would be no way to preserve the power and suppleness of her voice.

On 12 February 2012, three months after her surgery, Adele swept up six awards at the Grammys, including album of the year and song of the year. In her acceptance speech for best pop solo performance, she thanked Zeitels for restoring her voice. To most observers, it was a cheering comeback story, but for a handful of medical specialists it was a watershed moment. For years, vocal cord microsurgery had been considered risky. (In 1997, an unsuccessful surgical procedure left Julie Andrews’ already damaged voice beyond repair.) More than the physical risk, though, singers feared the damage to their careers that could follow if word got out. In the world of showbusiness, it was safer to be seen as a singer with a healthy young voice than as a one-time great with surgically repaired cords.

Now, Adele had suddenly swept away the stigma. In the years since, Zeitels’ business has boomed, along with those of many of his peers. They have no shortage of patients: there is an epidemic of serious vocal cord injuries in the performing arts. In addition to his work on Adele, Zeitels, who directs the Massachusetts General Hospital Center for Laryngeal Surgery and Voice Rehabilitation, has repaired the cords of more than 700 performing artists, including Sam Smith, Lionel Richie, Bono and Cher. Michael Bublé, Keith Urban, Meghan Trainor and Celine Dion have also had to quit touring to get their cords surgically repaired. In a mark of how attitudes to surgery have changed, both Smith and Bublé broke the news of their surgeries to their fans via Instagram.

There is no precise data on the number of performers who have gone under the knife over the years. But several surgeons told me they estimate that vocal cord surgery has been performed on thousands of pop, rock and classical singers, as well as on theatre and stage musical stars. Cancelled shows reverberate across social media and hit a struggling music industry hard. When Adele pulled out of her remaining two Wembley shows this summer, nearly 200,000 tickets had to be refunded. It’s unclear if she will ever tour again.

After Adele’s 2011 surgery, Zeitels became something of a celebrity. Occasionally, a reporter asked him if Adele was cured for good. He made no assurances, but told Channel 4’s Jon Snow that her surgically repaired voice “sounds smoother now than before”.

While the media was celebrating this miracle surgery, one woman in the music industry raised a dissenting voice. According to Lisa Paglin, a former opera singer turned voice coach, Zeitels had simply found a temporary fix; in the not too distant future, Adele would once again be forced off the stage and back into the operating theatre. It was a prediction that Paglin and Marianna Brilla, her coaching partner, were willing to stake their reputations on. The rash of vocal injuries silencing our most promising young talents, they argued, is too big a problem to be solved by microsurgery.

“How many surgeries would Dr Zeitels consider performing on Adele? Or on anyone? After surgery, unless a singer makes major changes, ‘return to performing’ means a return to the vocal abuse that put her/him on the operating table in the first place,” Paglin wrote, in the small trade publication Intermezzo. “Concerts – injury – surgery – rest – concerts – injury – surgery. Is this the life of a professional singer?”

When Adele cancelled the final nights of her recent tour, Brilla and Paglin felt saddened but vindicated. For more than a decade, they have been pushing for a revolution in the way that almost every modern performer has been taught to use their voice. After years of painstaking research in musical archives, early scientific journals and the classroom, Brilla and Paglin say they can deliver what medical science has failed to: a permanent fix for vocal burnout.

Their solution requires the revival of an all-but-vanished singing method that is not just beautiful to the ear, but also easy on the throat. Some of their ageing and beleaguered clients described it to me as a kind of fountain of youth. But their cure is not without controversy. It is based on a provocative theory that has been gaining ground among a small cadre of international talents: that we have all been singing completely wrong – even Adele.

Singing is a rough business. Every vocal performance involves hundreds of thousands of micro-collisions in the throat. The vocal cords – also known as vocal folds – are a pair of thin, reed-like, muscular strips located inside the larynx, or voice box, in the throat. They are shaped like a wishbone, and contain the densest concentration of nerve tissue in the body.

When we are silent, the cords remain apart to facilitate breathing. When we sing or speak, air is pushed up from the lungs, and the edges of the cords come together in a rapid chopping motion. The air causes the cords to vibrate, creating sound. The greater the vibration, the higher the pitch. By the time a soprano hits those lush high notes, her vocal cords are thwacking together 1,000 times per second, transforming a burst of air from her lungs into music powerful enough to shatter glass.

Beautiful singing requires lithe cords, but all that slapping together can wear down their fine, spongy surface and lead to tiny contusions. Over years of heavy use, nodules, polyps or cysts form on the vocal folds, distorting the sound they create. For a singer, the first sign of trouble is often the wobble. His pitch fluctuates on and off key because his ragged cords have lost their natural vibrato – their ability to resonate properly. Then there’s the “hole”, a point on the scale where a singer’s vibrating vocal cords fail to produce the proper tone. Try as he might, those notes will exit his mouth flat or, worse, as a barely audible gasp.

A vintage engraving of a view inside the throat. Photograph: Alamy Stock Vector

It was once unheard-of for a singer to perform with a faulty voice, but the opera world has recently been shaken by a trio of incidents in which the stars Rolando Villazón, Aleksandrs Antonenko and Roberto Alagna walked off stage mid-performance, unable to go on. Some opera singers complain of year-round cold symptoms, and legal steroid injections and other drugs are often used to get a struggling singer through a performance. But singing through the wear and tear can cause the lesions to burst and bleed, creating voice-ruining scars, which is what happened to Adele in 2011.

Voice specialists liken the physical toll on singers and stage performers to what athletes endure. Surgery to the professional singer’s vocal cords is what ligament reconstruction has become to the football player’s knee. Dusty theatres, stuffy airplane cabins, erratic eating and sleeping patterns, the stress of living off stingy contracts – all affect the vocal cords. Add to it the occupational hazard, at least in opera and classical music, of taking on roles that require you to sing above your natural range, and the cords become extremely susceptible to injury.

In 1986, the conductor, vocal coach and New York Times music critic Will Crutchfield lamented that vocal burnout was cutting short careers and diminishing the power of opera, “as audiences, by necessity, accustom themselves to hearing voices in poor condition”. Back then, Crutchfield saw that singers peaked in their 30s and then began to decline. But Adele, Trainor and Smith all underwent career-saving surgery in their 20s. Vocal burnout is afflicting amateurs, too. One veteran teacher in Italy told me that female students in their early 20s who want to sing like Adele or a young Whitney Houston are the ones who come down with vocal nodules. Another music teacher told me she recently had to instruct one of her 10-year-old students to stop singing and get his damaged cords checked by a specialist.

The rise in vocal injuries is linked to a change in what we consider good singing. Across all genres, it has become normal to believe that louder is better. (One reason that Adele is such a big star is because her voice is so big.) As a result, singers are pushing their cords like never before, which leads to vocal breakdown.

New waves of medical research into the causes of dysphonia, or the inability to properly produce voice, bear this out. In the west, vocal abuse is surprisingly common in all professions that rely on the voice , from schoolteachers to opera singers. Awareness of the problem is growing, but as Adele’s case demonstrated, and separate studies conclude, surgery is not necessarily a lasting fix.

Brilla and Paglin have been saying this for years. “You cannot solve the problem by simply relieving the symptom,” Brilla said. “It’s a motor problem. The singer has to understand it’s the way you’re running your engine” – the techniques they’re using to sing. “If you don’t fix the engine, it’s going to happen again.”

Teatro La Nuova Fenice, a 19th-century opera house built in the neoclassical style, sits at the top of the small hill town of Osimo in central Italy, just inland of the Adriatic Sea. In the grand lobby of the building is a marble plaque commemorating the night in 1927 when the Italian tenor Beniamino Gigli, one of the greatest talents of his era, performed here. Gigli packed concert halls across Europe and the Americas in a career that spanned five decades.

Gigli is an icon of the purer, more natural singing style that characterised a period when vocal injuries were almost unheard of, say Brilla and Paglin. They have a small teaching studio in a cul-de-sac below La Nuova Fenice. Brilla, a dramatic soprano with a fearless air, first became obsessed with the fragility of the human voice more than 50 years ago, as a teenage opera singer growing up in Pennsylvania coal country. A doctor there diagnosed her with a problem common among young singers with big voices: her vocal cords weren’t coming together properly. She had a hole. Over the next few decades, she cycled through nearly 30 teachers, including legends such as Antonio Tonini and Ellen Faull, trying to learn to sing in a style like Gigli’s – at once powerful, clear and sustainable over the course of many years.

Brilla met Paglin, a lyric soprano who appears small next to Brilla, while studying voice at Indiana University’s school of music. The two bonded over their love for Italian opera and their frustration with the way singing was taught, even by their legendary teacher Margaret Harshaw. Feeling that the giants of music instruction didn’t have the key to vocal longevity, Brilla and Paglin determined that they would be the ones to unlock the secret.

In 1977, Brilla won a prestigious Fulbright scholarship to travel to Italy to search for a way to sing beautifully without risking injury. There, she heard glimpses of perfect arias from older, mostly Italian opera singers who learned their craft in the early 20th century. These singers seemed to effortlessly produce clear, powerful musical tones, and so many of them were still performing with vigour well into their 60s, 70s and 80s. To Brilla, they held a clue to the vocal longevity lost to singers today.

Paglin soon joined her in Rome, where they started spending hours each day at the national sound archive, La Discoteca di Stato, listening to early recordings. They also scoured libraries for texts that discussed how operatic and classical singing techniques had changed over the centuries. When they weren’t researching, they were performing; big talents in their own right, they performed in many of the major opera houses and music halls of Italy and Austria. This put them in the presence of more masters, whom they peppered with questions. They also tracked down other ageing opera stars, teachers and conductors.

Their research pointed Brilla and Paglin to a surprising conclusion: that responsibility for the modern decline of the voice lay at the feet of Verdi, Wagner and Puccini. These three composers were the pop music sensations of their day. Music scholars credit them with being the first to challenge their singers to push their voices to new limits, in order to capture the emotional ups and downs their characters were feeling. Think of the teenage Japanese bride in Puccini’s Madama Butterfly, her heart breaking, desperately watching the seas for a sign her love will return, or the thunderous battle cries of the Valkyries in Wagner’s Ring cycle. If you’re going to kill off the main character of your show, you need genuine rage and pathos on stage.

But Brilla and Paglin heard something different – that the emotionally charged, full-throated, operatic singing style Verdi and Wagner made popular in the late 19th century – and that Puccini amped up even further in the early 20th century – had subsequently infiltrated all singing genres and public performances. With each passing decade, the style grew more extreme. To illustrate the point, when I visited the duo earlier this summer, Paglin pulled from their sprawling research library a file containing a series of images. The first was a photograph, taken in 1920, of the legendary Italian tenor Enrico Caruso mid-aria. Caruso seems to be enjoying himself, even as the camera flashes; it’s as if he’s talking to a friend, not baying at the audience. “This is natural singing,” Paglin said.

As she flipped from image to image, we travelled towards the present, a decade at a time. The photographs of the more contemporary singers – including the tenor Rolando Villazón, who has suffered multiple vocal injuries – looked like horror-movie stills: their mouths were wide open, eyes bulging, neck veins popping, as if they were screaming. There was none of Caruso’s easy calm.

Caruso and Gigli produced legendarily big sounds, but with an effort that today’s performers might deride as somewhat wimpy. Compare Caruso’s 1916 recording of O Sole Mio with Villazón’s 2010 rendition. Caruso’s is powerful, but not so powerful that the lyrics crash into one another and become indecipherable; and even at the height of the aria, he doesn’t drown out the strings. That Brilla and Paglin had identified this contrast wasn’t enough. They wanted to reverse-engineer exactly how Caruso and his contemporaries sang.

In 1983, Brilla convinced Maria Carbone, a retired Italian operatic soprano, to work with them. Carbone was nearing 80, but still had a powerful voice. While Carbone sang, Brilla would clasp Carbone’s abdomen to feel what was happening inside her body. Carbone started with an aria from Tosca. As her voice rose, hitting higher and higher notes, Brilla’s eyes widened. “I could feel this tick, tick. Tick, tick,” she recalled. It was the natural up-down release of her diaphragm. “Nothing else was happening.” Carbone’s ribcage wasn’t ballooning out as she sang, and there were no deep gulps of air, as is common with today’s big-voiced singers. More amazing still, the movement of Carbone’s abdomen while singing was just as quiet and rhythmic as when she spoke. “It was a discovery of what the perfect singer’s posture should be,” Paglin said.

Brilla added: “Whereas all the teachers in my life had been telling me to open, open, open” – to exaggerate her breathing and lunge into every high note to produce the biggest sound – Carbone “was demonstrating the opposite”.The root of the problem, they realised, is in classrooms. “Too many students graduate from conservatories who don’t know how to sing, and it’s leading to injury,” Brilla said. “We’ve got to stop this. It’s ass-backwards!”

It is not just singers whose careers are threatened by deteriorating vocal cords. In 1989, the Italian actor Maddalena Crippa momentarily lost her voice during a live performance of Shakespeare’s bloodiest work, Titus Andronicus. Crippa was playing Tamora, the vanquished queen of the Goths. After Tamora’s son is murdered before her eyes, Crippa said she “unleashed these uncontrollable cries”. But, for a moment, her next line wouldn’t come out. It was the first time in her acting career that Crippa’s vocal cords had failed her. “The suffering I felt was indescribable,” she told me.

That suffering continued for more than a decade. Crippa’s voice was no longer reliably crisp and sonorous, and a burning pain lingered in her throat. After visiting vocal coaches and throat specialists, she got the prognosis that all performers dread: nodules on her cords. Cortisone injections and voice exercises worked well enough to get her back on stage, but her confidence was shaken. “You mean you still don’t know how to use your voice?” she remembered thinking. “It’s demoralising.” Then, in 2002, at the suggestion of a fellow actor, Crippa visited Brilla and Paglin’s Osimo studio.

Unlike medical doctors, Brilla and Paglin don’t own a laryngoscope that allows them to peer into the throat. If someone comes to them with injuries, they treat the problem by ear. They sing a soft note and ask the student to match it precisely. They can hear in the response where the pitch is off-key, and where the damage is located on the cord. (When I spoke with Adele’s surgeon, Steven Zeitels, he demonstrated something similar, singing a scale to isolate where his own cord is damaged – a perturbation, as it’s called, the result of years of long hours in the classroom.)

The moment Crippa said hello, Brilla and Paglin knew there was something very wrong with her voice. She exuded tension, as if bracing for confrontation, and took big, gulping breaths before speaking. Brilla and Paglin often see this problem with singers; their vocal cords are so used to having great quantities of air shoved at them that the cords won’t respond without that force. “Once you start pushing, you’re condemned to push for the rest of your life,” Paglin told me. “Unless you learn a new way of doing it.”

In their studio, Brilla and Paglin instructed Crippa to lie on her back and produce a series of high notes, which Paglin demonstrated for me. It sounded like a faint squeaking, as if she was gently releasing air from the neck of a balloon. When Crippa was told to reproduce what Paglin called a “floating high C”, she protested, saying she couldn’t get that far up the scale. Finally, she gave it a try, producing a barely audible piff, followed by a more sustained tone. Hearing herself, Crippa broke down and cried. “They were tears of joy,” Crippa told me. “They touched a nerve deep inside me. I mean, this is my voice. My voice.”

Brilla and Paglin say they can restore most vocal cord problems naturally, via exercises that “massage out” the defect over time. They aim to stimulate the cords precisely where they aren’t coming together properly, and to break students out of the bad habits that cause problems in the first place: taking big gulps of air, tensing the throat and jaw muscles, forcing the mouth to open to exaggerated proportions, and the urge to scream out the high notes.

There are limits to what Brilla and Paglin claim to be able to do for an ailing artist. Paglin told me of a time when she was watching a singer perform on stage, and could tell there was something very wrong. She got a message to the singer that he urgently needed to see a doctor. He did, and was diagnosed with a form of throat cancer.

But their track record with other difficult cases has earned them a small international following. The veteran Italian stage actor Moni Ovadia was one of their earliest big-name success stories. Throughout his mid-40s, he performed up to 250 shows a year, in Europe and the US, but by 48 he was ready to quit showbusiness. His voice had become flat and raspy, and he found it physically painful to perform. He credits Paglin and Brilla with restoring his voice and his career. “They saved my life,” he told me. Today, at 71, he is a bull on stage, and can perform non-stop for up to three hours.

In May, at Brilla and Paglin’s studio in Osimo, I watched an aspiring dramatic soprano named Emanuela Albanesi rehearse the high-energy duet Mi Volete Fiera?, from Gaetano Donizetti’s comic opera Don Pasquale. There are few, if any, widely accepted standards for teaching singing, and many teachers complain that too many of their peers get jobs because of how they sound, not what they know. Paglin and Brilla mine the internet for teaching videos that concern them, such as one in which a soprano chides a student to open her mouth wider and wider as she sings an aria, in order to achieve more volume; not until the student plugs her fist into her mouth is the teacher satisfied.

Albanesi, however, sang with an ease that belied the strength of her highest notes. As she came to the final “grazie!”, I was expecting a thunderous, take-the-roof-off moment, but she never lost the disarming grin with which she performed. I thought of that photo of Enrico Caruso singing with such relaxed ease. I whispered to Brilla that it was the first time I had ever been able to make out each and every lyric in a such an intense operatic number. “I’m telling you,” she said. “We’ve cracked it.”

The question remains: could Brilla and Paglin’s approach permanently cure an artist like Adele by teaching her to sing in a more natural way? Steven Zeitels is dismissive of such an approach, and quick to defend Adele and his other clients against the contention that bad technique is causing their vocal problems. “People used to think if you needed an operation it meant you don’t know how to sing. The people I see – they know how to sing!”

Zeitels believes that medical specialists such as himself are becoming increasingly important to the arts, which he compared to other demanding physical pursuits. Any athletic endeavour will eventually take a toll if done for long enough, he said. “What’s terrific is we’re getting better and better at bringing people back.”

Specially trained vocal therapists have also restored performers to health through voice training, but medical experts advise taking this route only for minor vocal injuries, such as small nodules. Otherwise, they strongly suggest surgery. This attitude rankles Brilla and Paglin, who have cured artists such as the internationally renowned jazz singer Maria Pia De Vito, who suffered from vocal edema, a painful swelling of the cords, for which surgery is the generally recommended course of action. “What irony,” Paglin said. “There is an industry built around singers who harm themselves while singing, and there is another one built around fixing them up.”

Another renowned throat surgeon, Dr Robert T Sataloff, who has performed voice-corrective surgery on several Grammy Award winners, including Patti LuPone, bristles at the notion that surgery is not a sensible way to keep singers healthy. Combined with proper education on the dangers of improper singing technique, he believes it can keep people on stage for longer. “Is it perfect? No. And it probably never will be,” he told me. Like Zeitels, Sataloff drew a sporting analogy. Injury is inevitable – “and that’s when they end up in my office”.

Some conservatory teachers in Italy dismiss Brilla and Paglin’s natural-singing approach as heretical, and their disciples as a sect. Over time, the duo have made a number of enemies. An invitation in 2011 to teach a series of master classes at Rome’s Conservatorio di Musica Santa Cecilia, one of Italy’s top conservatories, met with near universal opposition among the faculty. The classes were popular with the students, but many teachers didn’t want them on campus. Edda Silvestri, the former director of Santa Cecilia, told me she didn’t recall any overt hostility towards the duo, but she did remember the rift Brilla and Paglin created between faculty and students. “Unfortunately, this is common when you try to introduce any new approach to a conservatory. They are conservative places,” Silvestri said. Elizabeth Aubry, the vice president of Italy’s most influential organisation of singing teachers, the Associazione Insegnanti di Canto Italiana, finds Brilla and Paglin’s critiques “ terrible”. She said the main objective of her organisation and its counterparts in the UK and US is to teach teachers precisely not to do damage.

For his part, Zeitels is working on a futuristic fix to dysphonia. Anyone who relies particularly heavily on their voice – schoolteachers, talkshow hosts, sales reps, preachers, lawyers, frazzled parents – is vulnerable to chronic raspiness, or to going hoarse. One of Zeitels’ patented innovations is to apply a biomaterial – a gel implant – in the tissue of damaged vocal cords to restore pliability. He sees it as a potentially huge breakthrough. “It will be just as important what you put into a vocal cord as what you remove,” he told a journalist in 2015.

But some of Brilla and Paglin’s students are thriving without such intervention, including Maddalena Crippa, who at 59 years old is in the midst of a remarkable second act. Her voice has been injury-free since she started working with Brilla and Paglin 15 years ago, and last May she wrapped up a critically acclaimed tour of L’Allegra Vedova, a one-woman-show based on a 1905 operetta. For 75 minutes each night, she sang and acted two roles, the husky-voiced Danilo and the high-pitched Anna, who at one point sing a virtuosic duet. Critics were impressed, with one raving that Crippa is still “a brilliant singer”.

Adele, however, is one of those rare figures in the arts. Her unique voice, and her story, are so big that many people believe that what she does (or doesn’t do) to correct her latest injury will determine future approaches to protecting the voice.

On 1 July, when news broke of Adele’s cancellations, Paglin sent me a Whatsapp message. She was frustrated by the press coverage. Recalling that Adele’s original surgery in 2011 had proved to be a huge PR victory for vocal-cord microsurgery, she worried that the message from Adele’s latest setback would be that, not to worry, a second or third surgery will get the star back on stage. “What makes matters worse is that the ‘mechanics’ are still convinced that all there is to it is to keep operating, while the singers themselves still talk about air travel, drafts, allergies and ‘stress’. #elephantintheroom could be a good hashtag,” she wrote, referring to what is wrong, as she sees it, with how people are taught to sing in the first place.

A few hours later, she sent me another note. She felt bad for Adele, and wanted to help. “We know how to fix Adele’s problems (sans surgery), and for good. If only we could talk with her.”

Main photograph: Sascha Steinbach/Getty

This article was amended on 12 August 2017 to correct an error. Dr. Robert T. Sataloff did not perform voice-corrective surgery on Neil Diamond. The singer only consulted Sataloff’s medical opinion.

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